The present invention relates to an ultrasonic generator system. More particularly, but not exclusively it relates to a generator system able to achieve and maintain a resonant torsional frequency to be applied to a waveguide.
A torsional waveguide has a large number of natural frequencies, only a few of which are useful. The majority of resonant conditions are in a flexural mode, which is not desirable.
Ideally, a conventional drive circuit could power an elongate thin torsionally vibratable waveguide. However, there are difficulties where it is desired to use a unique torsional mode resonance as this would need to be separated by a frequency difference of at least 1.0 kHz from any alternative resonant modes for a conventional circuit to suffice. In practice, such waveguides display alternative resonant modes within a few hundred Hz of a desired mode.
It is known from European Patent Application No. 1025806A to provide an ultrasonic surgical device in which the circuitry stores a frequency for a resonant condition and restores the signal to that condition whenever it detects a non-resonant condition.
This is not a flexible arrangement and it is not ideally suited to torsional vibration modes.
It is therefore an object of the present invention to provide a system which includes an intelligent frequency generating control circuit.